The rules for assemblers are the same as the rules for any language processor:
1. Correctness trumps speed
2. Make it easier for somebody to figure out how it works and how to change
it. Clever
code is fine, but document it adequately.
3. When you change platforms or change translators, that which was slow may
be fast
and that which was fast may be slow. Beware of optimizations that
disappear when you
upgrade or that impede maintenance.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List <[email protected]> on behalf of
Brian Chapman <[email protected]>
Sent: Tuesday, August 13, 2019 12:09 PM
To: [email protected]
Subject: Re: Instruction speeds
Thanks Charles and Steve.
Now that I am becoming a more experience assembler programmer, I have
wondered if I should be greatly concerned about instruction timings or
pipeline order, or just simply focus on readability and maintenance.
Especially since assembler programming is becoming a dying art. I think I
am only 1 of a handful of assembler programmers at my shop with hundreds of
mainframe programmers! I think you both answered my question. Thanks!
Thank you,
Brian Chapman
On Tue, Aug 13, 2019 at 11:39 AM Steve Smith <[email protected]> wrote:
> Write good code and forget about instruction timings. With any luck your
> code will have to perform on several generations of architecture and
> machines.
>
> There's a big difference between B- (base-index-displacement) branches and
> J- (or BR-) (relative address) instructions. Surely by now, this should go
> without saying. Regardless of whether they're "faster" or not, they are
> much better, and as that is well-documented, I won't belabor it.
>
> sas
>
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